JPH05221047A - Platen support structure in printer - Google Patents

Abstract

PURPOSE:To simplify a platen support structure and to accurately operate a platen in parallel to a platen base. CONSTITUTION:A platen base 1 and a platen 2 are joined in the vicinity of both ends thereof by a link 3 to constitute a quadric link and a spring 4 elastically transmitting the operation of the platen base 1 to the platen 2 is provided. A counter bore is provided to the platen base 1 or the platen 2 in matching relation to the hole of the link 3 at the joint of the link 3 and the platen base 1 or the platen 2 and a collar 21 is fitted in the counter bore through the hole of the link 3 and an adjusting joint is provided in the collar 21 through screws 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a platen support structure for a printing device.

[0002]

2. Description of the Related Art An example of the main part of a conventional printing apparatus is shown in FIG. 4 and its mechanism principle is shown in FIG. In FIG. 4, the print head 7 has a mask 8 fixed to the tip of the nose, and a platen unit 9 is arranged so as to face the print head 7, and an object to be printed is inserted between both to print. As shown in FIG. 5, the platen unit 9 connects a platen base 1 and a platen 2 via a link 3 in a vertically movable manner to form a four-bar link, and a spring 4 causes the platen base 1 to move the platen 2 in the vertical direction. Is urged to. The platen base 1 is provided with a detection lever 6 that detects the relative movement amount of the platen base 1 and the platen 2 when the platen base 1 and the platen 2 relatively move in the vertical direction, and a photo interrupter 5 that detects the movement of the detection lever 6. .. The need for the platen 2 to move toward and away from the print head is described in Japanese Patent Application Laid-Open No. 3-26566 of the same applicant.

A cam 13 and a bearing 14 are also provided on the opposite sides in the longitudinal direction of the platen base 1 shown in FIG. 4, the two cams 13 are connected by a shaft, and the rotation of the cam 13 causes the platen base 1 to move horizontally up and down. Move. Also, platen base 1
5, a link 3 and a spring 4 shown in FIG. 5 are provided at positions approximately symmetrical with respect to the print head 7 in the longitudinal direction.
A transmission shaft 15 is provided so that the platen base 1 and the platen 2 have the same relative movement amount in the vertical direction at one position and the platen 2 moves horizontally up and down.

Next, the operation will be described. When an object to be printed is conveyed to the printing mechanism section, first, the pulse motor 10 is rotationally driven, and the rotational power thereof is transmitted to the cam 13 via the pulley 11 and the belt 12. By the rotation of the cam 13, the bearing 14 mounted on the platen base 1 so as to be movable up and down is driven up and down as shown by the arrow, which causes the platen base 1 to move up and down, and through the spring 4 shown in FIG. The platen 2 is moved up and down to sandwich the print object between the platen 2 and the print head 7.

On the other hand, the platen base 1 is provided with a detection lever 6 which swings following the relative vertical movement of the platen base 1 and the platen 2, and the head gap is zero, to be precise, the platen 2 and the print head. The photo-interrupter 5 is shielded at a position where the object to be printed is pressed by a small amount by 7 and becomes a negative value. An appropriate head gap is set by controlling the pulse motor 10 based on the shielding signal of the photo interrupter 5. This enables clear printing even when the thickness of the printing object changes.

[0006]

However, in the above-mentioned conventional example, in order to move the platen 2 up and down horizontally, the links provided substantially symmetrically with the print head 7 as the center.
A platen drive mechanism consisting of 3 and a spring 4 is provided. The transmission shaft 15 is required in order to allow both links and the spring of the platen drive mechanism to work in perfect synchronization, which complicates the structure. Moreover, in the actual manufacturing process, a manufacturing error is always generated. Depending on the value of this error, horizontal vertical movement of the platen 2 cannot be ensured.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a platen support structure having a simple structure, absorbing manufacturing errors, and allowing the platen 2 to move parallel to the platen base 1. To aim.

[0008]

In order to achieve the above object, the present invention provides a support structure in a printing apparatus having a platen base 1 for supporting a platen 2 so as to be able to approach and separate from a print head. 1
And a spring 4 for elastically transmitting the approaching / separating motion of the platen base 1 to / from the print head to the platen 2 in the vicinity of both ends of the platen 2 by the links 3. At the connecting portion between the platen base 1 or the platen 2 and the platen base 1 or the platen 2, a counterbore hole is formed in the platen base 1 or the platen 2 in accordance with the hole of the link 3, and a hollow cylinder is passed through the hole of the link 3 to form the counterbore hole. An adjustment connection is included that fits and presses a screw through the hollow cylinder.

[0009]

FIG. 2 shows the principle of the mechanism of the present invention. Platen 2
The platen base 1 and the platen base 1 are connected at both ends by a link 3 to form a four-bar link, and the platen base 1 is connected by a spring 4.
Is transmitted to the platen 2. As a result, when the platen base 1 moves toward and away from the print head in parallel by the cams 13 and the bearings 14 provided at both ends in the longitudinal direction, this movement is transmitted to the platen 2 via the spring 4 as well. The joint link mechanism moves toward and away from the print head in parallel.

By the way, the above description is based on the assumption that the four-bar linkage is manufactured exactly as shown in the drawing. In the actual manufacturing, the accuracy of manufacturing the four pin mounting portions in FIG. 2 varies. For example, as shown in FIG.
If the distance L1 between the points and the distance L2 between C and D are different, the platen 2 is not parallel to the platen base 1. Even if L1 = L2, if M1 ≠ M2, the platen base 1 cannot operate in parallel.

Usually, the link 3 is written as a single item (writing a line for processing on the material) and processed, so that L1 = L2 is easily reached, but when M1 = M2 is not achieved. There are many. To achieve M1 = M2, any 3 out of 4 points
Attach the points, eg A, B, and C according to the drawing instructions, and adjust the remaining D points so that M1 = M2, align with the holes of the link 3, and in this case, make a spot facing hole in the platen 2. , M1 = M2 can be achieved by fitting a hollow cylinder (referred to as a collar) into the counterbore through the hole of the link 3, and the platen 2 can operate in parallel with the platen base 1.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 shows a perspective view of an embodiment of the present invention, and FIG. 3 shows a cross section taken along line XX of FIG. The same reference numerals as those in FIG. 4 represent members having the same function. Platen base 1 has an inverted U section
A holding member 17 of the platen 2 is inserted into a platen insertion opening 16 formed on the top surface of the platen-shaped member.

The platen 2 has a print receiving portion 18 having a semicircular cross section.
The holding portion 17 is formed so as to project from the bottom portion of the. The side wall of the platen base 1 is linked to the holding portion 17 of the platen 2.
3 is provided with an opening 19 through which a stud 20 or a collar 21 for engagement with the plate 3 penetrates.
The dimensions are set so that the stud 20 and the collar 21 do not come into contact with each other even during the operation of.

As shown in FIGS. 1 and 3, the links 3 are U-shaped, and each side surface of the platen base 1 constitutes a four-bar linkage mechanism. Link 3 and platen base 1 or platen 2 can be connected with stud 20
Or made by collar 21 and screw 23. Also, FIG.
As shown in FIG. 4, a spring 4 is provided in the center of the link 3 near the stud 20 or the collar 21 that connects the platen base 1 and the link 3 to operate the platen base 1 with the stud 20 and the collar 21 and the spring 4. It is elastically transmitted to the platen 2 via. The studs 20 are used at three points on one side of the platen base 1 as shown in FIG. 1, and the remaining one point and four points on the other side are connected by a collar 21 and a screw 23.

As shown in FIG. 3, one end of the collar 21 is fitted with a counterbore 22 which is formed in accordance with the hole of the link 3 and is screwed.
23 prevents it from coming off.

Next, the operation will be described. When both ends of the platen base 1 are moved in parallel by the cam 13 and the bearing 14, this movement is transmitted to the link 3 via the stud 20 and the collar 21 connecting the platen base 1 and the link 3 in FIG. It is transmitted to the platen 2 via the spring 4. Then, as shown in FIG. 1, the platen 2 approaches and separates from the print head in parallel to the platen base 1 by a four-node link mechanism constituted by two links 3 provided in the longitudinal direction of the platen base 1.

When the top of the platen 2 hits the object to be printed,
Although the movement of the platen 2 stops, the pressing of the platen base 1 continues, the spring 4 contracts, the relative movement between the platen base 1 and the platen 2 occurs, the detection lever 6 swings, and the platen 2 locates the object to be printed. The photo interrupter 5 is shielded at the position where the fixed amount is pressed. An appropriate head gap is set by controlling the pulse motor 10 based on the shielding signal of the photo interrupter 5. This enables clear printing even when the thickness of the printing object changes.

Further, as shown in FIG. 1, the platen base 1
Connect link 3 and 3 points with stud 20 on one side of
Since the remaining one point and the other four points on the other side surface are connected by the collar 21 and the screw 23 whose position can be adjusted, the through hole of the link 3, the platen 2 and the link 3 of the platen base 1 are connected. It is possible to prevent tilting of the platen 2 due to subtle variations in component accuracy, and astringency of the connecting portion.

Although this embodiment shows the case where the platen 2 moves up and down in FIG. 1, it is also possible to move horizontally.
It is possible to perform a parallel movement operation in the direction of approaching or separating from the print head.

[0020]

As is apparent from the above description, according to the present invention, the platen 2 and the platen base 1 are connected at both ends by links 3 to form a four-bar link, and the operation of the platen base 1 is controlled by the platen 2. The platen 2 can be operated in parallel with the platen base 1 by providing the spring 4 that elastically transmits to the platen, and the link connection part has an adjustable structure. Therefore, the structure is simple and theoretically only. Instead, the platen 2 can be operated in parallel with the platen base 1 in practice.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention.

FIG. 2 is a diagram showing the principle of the mechanism of the present invention.

3 is a sectional view taken along line XX of FIG.

FIG. 4 is a view showing a conventional vertical movement mechanism of a platen.

5 is a diagram illustrating the principle of the vertical movement mechanism of FIG.

[Explanation of symbols]

 1 Platen base 2 Platen 3 Link 4 Spring 20 Stud 21 Collar 23 Screw

Claims (1)

[Claims] 1. A support structure in a printing apparatus having a platen base (1) for supporting a platen (2) so as to be able to approach and separate from a print head, in the vicinity of both ends of the platen base (1) and the platen (2). A link (3) to form a four-bar link, and a spring (4) for elastically transmitting the approaching and separating actions of the platen base (1) to and from the print head to the platen (2) is provided. At the connecting portion between (3) and the platen base (1) or the platen (2), a counterbore hole is opened in the platen base (1) or the platen (2) in accordance with the hole of the link (3) to form a hollow. Link the cylinder to the link (3)
A platen support structure in a printing apparatus, comprising an adjustment connection part which is fitted into the counterbore hole through the hole of and is pressed through a screw in the hollow cylinder.